97 Olds 88LS slight skipping going uphill

[earl84]

First post, great forum with lots of nice as well a sknowledgeable folks. I have searched the forum for this but no luck on this specifically.
I have had this car for about 3 years. Gone through its mechanical issues, but this one has bothered me for a while.
Only happens going uphill on steep slopes. Very slight skip, like it's having a misfire, but does not ever throw a code, capture the Check Engine light, nothing. Runs absolutely perfect on flat or slight hills. Does not matter if it's in Cruise Control or not.
I have recently had issues with the MAF sensor and had it in the shop twice. MAF Sensor was replaced along with some wires that were bare and shorting out and before that had the catalytic converter and Crankshaft Position Sensor replaced. I have a great mechanic. While there he also checked fuel pressure, Ignition Control Module, and had it hooked up to diagnostic tool on his computer and noted nothing else wrong. To be honest I didn't ask about this issue.
Sorry for the long first post. Any ideas, anyone?

[maxwedge]

Bad plug or dirty injectors most common cause of this.

[earl84]

I finally got around to getting my plugs and wires changed. The old plugs looked great, doesn't appear there is any issue there. I ran a can of Seafoam through also. Still have the issue.
I took it to a mechanic who drove it with his computer hooked up and he could not diagnose the issue. Said I may have to drive until it throws a code or breaks harder. Great. He said it does not seem like a tranny issue, but engine. Hmm.
Maybe Ignition Control Module change or buy one coil pack and swap it around until the problem goes away is the next step. Can these be tested first,and if so, how. Any other suggestions? Other things I have done: changed transmission filter, changed fuel filter (it was pretty disgusting). My other thought was fuel pump, but the mechanic said it tested with good pressure in the 45-55 psi range. The fuel level indicator isn't working right, so I was sort of thinking of changing that all at once anyway.

I appreciate any and all input.

[maxwedge]

These symptoms can be caused by dirty injectors causing a lean mixture, this would show up on the scan during the plus or minus fuel trim readings, if lean the pcm would try to enrichen the mixture by increasing injector dwell time.

[earl84]

I have a friend with an Autoscan scanner, their most expensive one at Autozone. Are these things that this scanner can pick up or do I need a computer based program? Also, how do I know what "Normal" readings should be to know if the plus or minus trim readings are incorrect or if they are good?
I already ran a can of Seafoam through the car, is there something else I can do to really clean them?

Thanks for your input Maxwedge, I really appreciate it.

[maxwedge]

If the engine is too lean the fuel trims, short term especially, would be plus 10 or more. Can't tell you if that scanner will pick that up but it should.